Three-dimensional Geometric Model Research Articles

Phenotypic characterization of liver tissue heterogeneity through a next-generation 3D single-cell atlas

Three-dimensional (3D) geometrical models are potent tools for quantifying complex tissue features and exploring structure–function relationships. However, these models are generally incomplete due to experimental limitations in acquiring multiple (> 4) fluorescent channels in thick tissue sections simultaneously. Indeed, predictive geometrical and functional models of the liver have been restricted to few tissue and cellular components, excluding important cellular populations such as hepatic stellate cells (HSCs) and Kupffer cells (KCs). Here, we combined deep-tissue immunostaining, multiphoton microscopy, deep-learning techniques, and 3D image processing to computationally expand the number of simultaneously reconstructed tissue structures. We then generated a spatial single-cell atlas of hepatic architecture (Hep3D), including all main tissue and cellular components at different stages of post-natal development in mice. We used Hep3D to quantitatively study 1) hepatic morphodynamics from early post-natal development to adulthood, and 2) the effect on the liver's overall structure when changing the hepatic environment after removing KCs. In addition to a complete description of bile canaliculi and sinusoidal network remodeling, our analysis uncovered unexpected spatiotemporal patterns of non-parenchymal cells and hepatocytes differing in size, number of nuclei, and DNA content. Surprisingly, we found that the specific depletion of KCs results in morphological changes in hepatocytes and HSCs. These findings reveal novel characteristics of liver heterogeneity and have important implications for both the structural organization of liver tissue and its function. Our next-gen 3D single-cell atlas is a powerful tool to understand liver tissue architecture, opening up avenues for in-depth investigations into tissue structure across both normal and pathological conditions.

Three-Dimensional Accurate Geometric Modeling and Mechanical Analysis of Wire Mesh for Deployable Antennas

Wire meshes are widely used in deployable antennas, and the structure of the wire mesh directly affects the structural and electrical properties of the antenna. This study proposes a set of automated geometric modeling and mechanical analysis processes to realize the automated mechanical analysis and design of complex wire mesh structures. First, considering the tilt in the wire mesh structure owing to the traction of the underlap on the loop, a three-dimensional (3D) geometric model of the repeating unit of the wire mesh structure was established using periodic cubic spline curves. Subsequently, a method using sensitivity matrix adjustment is proposed to eliminate the interstructure inlay phenomenon, and an optimization model is established. The vector superposition method established a 3D geometric model of the overall wire mesh structure without an inlay problem. Finally, a finite element model of the wire mesh considering the contact problem was established by the adaptive matching method for contact pairs of the finite element model of the wire mesh. Mechanical simulation experiments were carried out on the model, comparing the theoretical analysis with the experimental results and verifying its reasonableness.

Experimental study on determining the degree of bone healing by wall thickness ratio analysis

To verify the reliability and accuracy of wall thickness ratio analysis to determine the degree of bone healing, fracture models were established with 6 beagles. X-ray, micro-CT, and CT scans were performed at 24 weeks. The healthy side and the affected side were used to simulate the three-dimensional geometric model after internal fixation, and the mesh was divided. The mean and median CT wall thickness values were obtained through the wall thickness analysis. X-ray, CT, micro-CT, and gross appearance were used to determine the degree of bone healing, which was compared with wall thickness analysis. There was a positive correlation between the average CT value and the median wall thickness. The correlation coefficient analysis of the median wall thickness ratio (R2) and healing index ratio (R3) showed a positive correlation. The results of the wall thickness ratio (R2) and the healing index ratio (R3) were used to determine bone healing, and the results were consistent with the results of the actual mechanical test and image analysis. The results of wall thickness ratio analysis were significantly correlated with the degree of bone healing. This method is simple, rapid, and practical to analyze and judge the degree of bone healing.

A Rapid Method of Integrated Aeropropulsive Analysis for the Conceptual Design of Airbreathing Hypersonic Aircraft

A special feature of airbreathing hypersonic aircraft is the complex coupling between aerodynamic and propulsive performances. This study presents a rapid analysis methodology for the integration of these two critical aspects in the conceptual design of airbreathing hypersonic aircraft. Parametric modeling is used to generate a three-dimensional geometric model of an aircraft. The integrated aerodynamic and propulsive analysis is performed using a loosely coupled method. The aerodynamic analysis uses Euler equations to solve the inviscid aerodynamic forces, while the viscous forces are estimated using semi-empirical engineering methods. The propulsion system is modeled using hybrid one- and three-dimensional approaches. The inlet aerodynamic performance is simulated using three-dimensional simulation based on the Euler equations. The ramjet performance is estimated using a quasi-one-dimensional mathematical model. Nozzle simulation is performed using a one-dimensional plume method. The entire computational process is integrated and can be run automatically. The usefulness of the method is demonstrated through aerodynamic and propulsive performance evaluations in the conceptual design of a notional airbreathing hypersonic aircraft.

Multi-hazard assessment of a masonry railway bridge in landslide areas

Earthquakes and landslides pose a high risk to road infrastructure due to unfavorable geological conditions in conjunction with extreme climate events. In particular masonry arch bridges are very often affected by natural events such as floods, landslides, and earthquakes, causing the partial or total collapse of the bridge. To determine the vulnerability to the multiple hazards related to a specific area, a multidisciplinary approach that allows to analyze the different issues is needed. Non-destructive survey strategy based on the study of geo-morphological area, in situ tests and accurate numerical modelling are required to perform a multi-hazard vulnerability assessment of a masonry bridge in a landslide area. In this paper, a multi-disciplinary multi-sensor methodology is proposed based on photogrammetric and thermographic surveys, for the definition of an accurate georeferenced three-dimensional geometrical models of the bridge for a reliable definition of a numerical model to be adopted for the structural assessment of the bridge consistent to a multi-hazard scenario. Namely, a discrete macro-element models (DMEM) based on the software HiStrA Bridge has been applied to determine the soil-structure interaction associated to landslides events. The masonry arch railway bridge chosen for this study is located in a complex geological and geomorphological context. In fact, earth landslides affecting the bridge and poor physical-mechanical characteristics create the conditions for a complex case study. The objective of this study is to assess the vulnerability of masonry bridges subject to the combined effects of landslides, and hydraulic hazard due to bridge occlusion by the modeling of these effects.

The passive safety system of a high-speed multiple-unit train

The designing of modern high-speed multiple-unit trains in Ukraine should be carried out accounting for passive safety systems (PSSs) which include energy absorption devices (EADs). In the cases of trains collisions with obstacles these systems must automatically work to increase the passenger transportation safety, to reduce the risk of injury and death of passengers and service personnel, to minimize rolling stock damage. On the base of European experience in power head passive protection, a three-dimensional geometric model of the domestic power head frontal part with energy absorption devices containing cellular elements was developed. The protective devices for the power head and energy absorption devices installed in inter-car connections were proposed using the experience of development of the EP20 locomotive energy absorption device and results of its prototype crash test. The scientific methodology was developed to evaluation the EAD parameters. Finite-element models for studying the plastic deformation of EAD designs at impact and discrete-mass mathematical models for studying the dynamic loading of reference multiple-unit train vehicles in emergency collisions were developed in accordance with the DSTU EN 15227 requirements. As a research result, the parameters of the EAD designs have been obtained and compliance of the developed passive safety system with regulatory requirements has been proven.

Wall thickness analysis method for judging the degree of lower extremity long bone healing

To evaluate the possibility of judging the degree of bone healing by wall thickness analysis provide reference for quantitative analysis of bone healing. Patients with lower limb fracture from April 2014 to October 2019 were recruited and divided into bone healing (group A), poor bone healing (group B), and nonunion (group C). Models were built in Mimics 20.0 with DICOM 3.0 data obtained from patient’s CT. Three-dimensional geometric models of unaffected limb and affected limb after simulated removal of internal fixation were established, corresponding to basic phase and simulated phase, respectively. Wall thickness analysis was performed to obtain median wall thickness after meshing. R2 (median wall thickness ratio), R4 (CT value ratio), and R5 (healing index ratio) were obtained by calculating the ratio of each value in simulated phase to that in basic phase. Receiver operating characteristic curve analysis was used to evaluate the ability of Wall Thickness Analysis to indicate fracture healing. 112 CT scans of 79 patients were included in the study. The frequency of categorization in groups A, B, and C was 49, 37 and 26, respectively. The median R2 in groups A, B, and C was 0.91, 0.80, and 0.67, respectively (group A > group B > group C, all P < 0.05). The best cutoff point for R2 in predicting bone healing was 0.84, and predicting bone nonunion was 0.74. The Wall Thickness Analysis can be used to quantitatively evaluate fracture healing state, with median wall thickness ratio as a more intuitive and reliable judgment index.

Three-Dimensional Numerical Analysis and Operational Optimization of High-Efficiency Sedimentation Tank

The high-efficiency sedimentation tank has a wide range of application prospects in industrial wastewater treatment due to its small footprint, strong resistance to shock loads, and high efficiency. However, the complex flow field distribution inside significantly affects the treatment performance of the high-efficiency tank. In this study, a three-dimensional geometric model of the high-efficiency sedimentation tank was constructed based on an engineering prototype. The corresponding solid–liquid two-phase, whole-process computational fluid dynamics (CFD) model for the high-efficiency sedimentation tank was established using the realizable k-ε turbulent model and the multiple reference frame (MRF) method. The internal structures of the flocculation zone, plug-flow zone, and clarification zone were optimized, and then the influence of operational process conditions on the flocculation treatment performance was investigated. The results indicate that, for the given engineering model, the average turbulent kinetic energy k in the flocculation zone exhibits a trend that initially increases and then decreases with the increase in the diameter and height of the draft tube. The optimal hydraulic conditions for the flocculation zone are achieved when the diameter of the draft tube is 2.5 m and the height is 3.5 m. The average turbulent kinetic energy dissipation rate in the plug-flow/clarification zone tends to decrease first and then increase as the height of the water tunnel and water-retaining weir increases. The optimal hydraulic conditions for the plug-flow and clarification zones are achieved when the height of the water tunnel is 1.0 m and the height of the water-retaining weir is 1.6 m. Under optimal operating conditions (dosage of dense media particles: 40 mg/L, stirring rate: 30 rpm, and inlet velocity: 0.72 m/s), satisfactory overall hydraulic conditions can be achieved throughout the entire high-efficiency sedimentation tank. Comparisons between a high-efficiency settling tank and a conventional clarifier for the treatment of circulating water sewage in a practical implementation reveals that the ballasted high-efficiency settling tank has advantages in terms of high hydraulic loading, high removal efficiency of hardness, small footprint, and low doses of flocculant. This research will provide reference values for the design and operation optimization of high-efficiency sedimentation tanks.

A hybrid modeling method for predicting the cutting force in whirlwind milling of lead screw

Analyzing the cutting force in the process of lead screw whirlwind milling can help us understand the processing quality and processability. Whirlwind milling is a process in which multiple cutting tools are driven by the cutter head to sequentially cut and process the workpiece. The cutting force changes periodically in the process of lead screw whirlwind milling. Analyzing the cutting force of the nth cutting needs to consider the influence of the previous n-1 cutting. This paper employed a hybrid method combining mathematical modeling and finite element analysis to predict the cutting force in lead screw whirlwind milling. Firstly, the tool motion path of lead screw whirlwind milling is analyzed by considering the influence of cutter inclination angle and relative tool-workpiece motion. The relationship between the nth tool path and the (n-1)th tool path is analyzed by considering the feed motion of the tool and the rotation motion of the workpiece. Furtherly, mathematical models of the nth tool path and the (n-1)th tool path are established. Then, based on the established mathematical models, the three-dimensional geometric model of the tool and workpiece is established by three-dimensional software. The establishment of the workpiece geometry model considers the influence of the previous n-1 cutting. The tool geometry model rotates along the (n-1)th cutting path, and the tool intersects the workpiece. Finally, the finite element model of lead screw whirlwind milling is established based on the above three-dimensional geometric model. The periodical cutting force in the lead screw whirlwind milling is obtained by simulating the nth cutting with the finite element model. The relevant lead screw whirlwind milling experiment was carried out to verify the reliability of the model prediction. The appropriate processing parameter range of lead screw whirlwind milling is obtained through the process parameter optimization.

A novel in silico Nuss procedure for pectus excavatum patients

The purpose of this study is to suggest a novel in silico Nuss procedure that can predict the results of chest wall deformity correction. Three-dimensional (3D) geometric and finite element model of the chest wall were built from the 15-year-old male adolescent patient’s computed tomography (CT) image with pectus excavatum of the mild deformity. A simulation of anterior translating the metal bar (T) and a simulation of maintaining equilibrium after 180-degree rotation (RE) were performed respectively. A RE simulation using the chest wall finite element model with intercostal muscles (REM) was also performed. Finally, the quantitative results of each in silico Nuss procedure were compared with those of postoperative patient. Furthermore, various mechanical indicators were compared between simulations. This confirmed that the REM simulation results were most similar to the actual patient’s results. Through two clinical indicators that can be compared with postoperative patient and mechanical indicators, the authors consider that the REM of silico Nuss procedure proposed in this study is best simulated the actual surgery.

Computational fluid dynamics of upper airway aerodynamics for exercise-induced laryngeal obstruction: A feasibility study.

Use of computational fluid dynamic (CFD) simulations to measure the changes in upper airway geometry and aerodynamics during (a) an episode of Exercise-Induced Laryngeal Obstruction (EILO) and (b) speech therapy exercises commonly employed for patients with EILO. Magnetic resonance imaging stills of the upper airway including the nasal and oral cavities from an adult female were used to re-construct three-dimensional geometries of the upper airway. The CFD simulations were used to compute the maximum volume flow rate (l/s), pressure (Pa), airflow velocity (m/s) and area of cross-section opening in eight planes along the vocal tract, separately for inhalation and exhalation. Numerical predictions from three-dimensional geometrical modeling of the upper airway suggest that the technique of nose breathing for inhalation and pursed lip breathing for exhalation show most promising pressure conditions and cross-sectional diameters for rescue breathing exercises. Also, if EILO is due to the constriction at the vocal fold level, then a quick sniff may also be a proper rescue inhalation exercise. EILO affects both the inspiratory and the expiratory phases of breathing. A prior knowledge of the supraglottal aerodynamics and the corresponding upper airway geometry from CFD analysis has the potential to assist the clinician in choosing the most effective rescue breathing technique for optimal functional outcome of speech therapy intervention in patients with EILO and in understanding the pathophysiology of EILO on a case-by-case basis with future studies. 4.

Mechanism of blood flow energy loss in real healthy aorta using computational fluid-structure interaction framework

Blood flow energy loss may correlate with the occurrence of vascular diseases. However, the mechanism of blood flow energy loss is still not fully explored. The objective of the present study is to reveal the mechanism of energy loss of blood flow in the healthy aorta. Two patients without aortic diseases are retrospectively screened from a clinical hospital. The computed tomography image is used to inversely reconstruct a three-dimensional geometric model of the healthy aorta. Non-invasive clinical measurements are applied to determine patient-specific boundary conditions. The fluid-structure interaction method is adopted to acquire high-resolution hemodynamics. A novel method is proposed to calculate the blood flow energy loss caused by aortic wall deformation. The distribution of blood flow validates the accuracy of the above computational framework, which could capture more than 90% of blood flow energy loss. Viscous friction of blood flow is the primary cause of energy loss, followed by aortic wall deformation, and finally turbulent dissipation. Energy loss due to viscous friction and wall deformation mainly occurs on the aortic vessel wall. The sum of these two energy losses approximates the total energy loss and may be associated with the initiation of aortic lesions. Besides, we find that the buffering efficiency of the real healthy aorta is about 80%. The mechanism of aortic blood flow energy loss is uncovered and these findings would inform the new hemodynamic markers and clinical assessment tool for the vascular wall.

Design of customized implants and 3D printing of symmetric and asymmetric cranial cavities

A methodology has been developed in this work to design customized cranial implants from computed tomography (CT) scan images for symmetric as well as asymmetric defects. The two-dimensional CT scan images were converted into three-dimensional geometric models using software packages. Two cases of cranial cavities at different locations were considered for implant design using two different approaches. Case 1 is having a symmetric cranial cavity while Case 2 has an asymmetric frontal cranial cavity. The craniums with defects were 3D reconstructed. Customized cranial implants were made for the two cases. In Case 1, symmetry was used to design the cranial implant. Symmetry cannot be used in Case 2. In Case 2, the implant was designed by blending from the surface available adjacent to the missing portion of the cranium. 3D reconstructed bone models and customized implants were 3D printed in poly-lactic acid (PLA) using a fused deposition modeling process for form and fit evaluation. Finite element analysis was performed to compare the mechanical behavior of bone, and the two biomaterials – polyether ether ketone (PEEK), and Ti6Al4V. Static structural finite element analysis was performed to simulate the impact of falling off a bicycle with an impact on the cranial implants in the two cases. The load was modeled as a normal force acting on the surface of the implant. It was found that the stresses in the titanium alloy are comparable to those of PEEK for both the cases. However, the strains and deformation were found to be much smaller compared to those in PEEK. Therefore, the titanium alloy is the material of choice for both the cases among the materials under consideration. The designed implants are solid hence may face the challenge in bone ingrowth. In future studies, the implant can be made porous by incorporating a lattice structure to enhance osseointegration and promote bone ingrowth. Implants for both symmetric and asymmetric defect cases in cranium were successfully designed.

A practical hybrid approach to the problem of surveying a working historical bell considering innovative measurement methods

The article proposes using a novel hybrid measurement method, with expected precision results, to determine the characteristic of the historic, 17th-century bell. In an interdisciplinary approach, modern and non-invasive physical and chemical measurement methods were used. Based on the monitoring (measurements and laser scanning), a three-dimensional geometric model was built to calculate the bell size and analyze its condition depending on material consumption. Next, chemical measures of the bell samples were carried out to determine the material properties. For that purpose, advanced precision microscopic techniques were used. Based on the geometric model and chemical studies, the material properties and density of the bronze were determined using additive assumptions. Measurement accuracy and data quality were evaluated statistically. The method allows reliably determining the bell's weight without needing to dismantle it or external intervention. The approach is helpful for practitioners performing conservation work on such objects.

Stability Analysis of a Vehicle–Cargo Securing System for Autonomous Trucks Based on 6-SPS-Type Parallel Mechanisms

Stability prediction of the securing system for autonomous trucks is an important prerequisite for achieving safety monitoring of large cargo transportation and improving logistics efficiency. Considering the side slide risk of large cargo and the inability to predict stability using the existing under-constrained friction securing model, this paper proposes a new vehicle–cargo securing model based on the 6-SPS parallel mechanism. By establishing an analytical 3-DOF model, the dynamics performance of the vehicle–cargo system is analyzed based on the response solution under sinusoidal excitations. To verify the correctness of the analytical model, a multi-body dynamics model of the whole vehicle–cargo system based on the three-dimensional geometric model and the 6-SPS parallel mechanism is established for simulation in ADAMS. According to road class, pavement roughness is modeled by a white noise power spectrum method as the excitation in the simulation. The results show that the dynamics response of the analytical model accords well with that of the simulation model, with relative errors of 8.34% and 0.036% in amplitude and frequency, respectively. The proposed method can provide theoretical support for accurate stability prediction and for achieving safety monitoring of large cargo transportation for autonomous trucks.

A New Method to Three-dimensional Dual Medium Geometry Model Construction

Dual medium geometric model is widely used in soil and rock mass environment, which can only reflect the material exchange between cracks and matrix. The dual medium geometric model ignores the hydraulic relationship between the pores and cracks. The paper develops a new method to construct the three-dimensional dual medium geometry model. This method is completely written by Matlab scripting language, can describe the real spatial distribution state of fracture in bedrock. In the method, three-dimensional random fracture network geometric models with different parameters and three-dimensional porous media geometric models with Berlin Noise characteristics are constructed respectively, and then use the three-dimensional direct superposition method to construct the dual medium geometric model. The paper introduces the construction of three-dimensional random fracture network geometry model, three-dimensional porous media geometric model and the dual medium geometric model by direct superposition method. This research is of great significance to the construction of dual medium model and numerical simulation in related fields.

FREQUENCY ANALYSIS OF AN ARM OF MACPHERSON SUSPENSION ON A PASSENGER CAR

The smoothness, ride comfort, safety and handling of the car depends on the manner of suspension design and its corresponding details. One of main functions of the arm and the rubber bushings mounted on it is to reduce the vibrations and the noise transferred from the road to the passenger car components. This article presents the results of a frequency analysis of an arm of the MacPherson front independent suspension. For this purpose, three-dimensional geometric models of the arm and rubber bushings are created via finite element analysis (FEA) software SolidWorks, where Skoda Octavia passenger car was used as a prototype. The axial, radial and torsional stiffness of the rubber bushings were determined through analytical dependences and FEА. The obtained results had been used for calculation of the natural frequencies and mode shapes of the arm which were compared with experimentally obtained data.

Renovisceral artery alterations due to branched endovascular aortic repair and respiratory-induced deformations

ObjectiveThis study quantified respiratory-induced dynamics of branch vessels before and after thoracoabdominal aortic aneurysm (TAAA) branched endovascular aneurysm repair (bEVAR). MethodsPatients with TAAA were recruited prospectively and treated with bEVAR, predominantly with Zenith t-Branch and BeGraft Peripheral PLUS bridging stents. Using SimVascular software, three-dimensional geometric models of the vessels and implants were constructed from computed tomography angiograms during both inspiratory and expiratory breath-holds, preoperatively and postoperatively. From these models, branch take-off angles, end-stent angles (transition from distal end of stent to native artery), and curvatures were computed. Paired, two-tailed t tests were performed to compare inspiratory vs expiratory geometry and pre- vs postoperative deformations. ResultsWe evaluated 52 (12 celiac arteries [CA], 15 superior mesenteric arteries [SMA], and 25 renal arteries [RA]) branched renovisceral vessels with bridging stents in 15 patients. Implantation of bridging stents caused branch take-off angle to shift inferiorly in the SMA (P = .015) and RA (P = .014) and decreased the respiratory-induced branch angle motion in the CA and SMA by approximately 50%. End-stent angle increased from before to after bEVAR for the CA (P = .005), SMA (P = .020), and RA (P < .001); however, respiratory-induced deformation was unchanged. Bridging stents did not experience significant bending owing to respiration. ConclusionsThe decrease in respiratory-induced deformation of branch take-off angle from before to after bEVAR should decrease the risk of device disengagement and endoleak. The unchanging respiratory-induced end-stent bending, from before to after bEVAR, means that bEVAR maintains native vessel dynamics distal to the bridging stents. This factor minimizes the risk of tissue irritation owing to respiratory cycles, boding well for branch vessel patency. The longer bridging stent paths associated with bEVAR may enable smoother paths subject to less dynamic bending, and potentially lower fatigue risk, compared with fenestrated EVAR.

A Smart Floodlighting Design System Based on Raster Images

This article describes a system for designing floodlighting of objects using computer graphics. Contrary to the currently used visualisation tools, the developed computer application is based on the daytime photography of the object and not on its three-dimensional geometric model. The advantage of the system is the high photorealism of the simulation, with no need to create a collage of visualisation with photography. The designer uses the photometric data of luminaires, and their photometric and colourimetric parameters are defined. With the system it is possible to perform a precise lighting analysis—the distribution of illuminance and luminance—both for the entire facility and in any plane or point. The system also analyses the total installed power of a given design solution. The system application is presented as an example in the form of a case study. This example shows the features of the system and further expected directions of development.

A novel modeling and simulation for the electro-thermal conversion analysis of graphene-coated knitted fabric

Electrical heating fabrics that possess the excellent characteristics of lightweight, soft, and rapid heating were exploited to address the warmth problem in the cold winter. In this study, a stretchable and effective graphene-decorated weft-knitted fabric heater was developed by spray-drying approach. The graphene-decorated weft-knitted fabric has good stretchability with the strain of 124%, and a high thermal response that reached 206°C with voltage of 10 V. The heating performance of the graphene-decorated weft-knitted fabric remained unchanged at 20 cycles. Furthermore, a three-dimensional geometric model of graphene-decorated weft-knitted fabric was constructed. Mathematical modeling and visual simulation analysis were carried out to explore the electro-thermal coupling behavior. The electro-thermal conversion simulation results are basically consistent with the experimental data. The results offer an approach to design flexible and wearable electrical heating fabrics for thermal management.